Yes, I am not entirely sure yet what would be the best user interface for this yet, but animation loops are a must!

Note that currently, it is already possible (though very clunky) to achieve something similar. Suppose you want to copy all the frames 1,2,3,4 into 5,6,7,8. You can do this:

On frame 1, use the rectangle of selection to select everything on frame 1.

On frame 2, hold "Shift" and use the rectangle of selection to select everything on frame 2, without losing the selection on frame 1.

Repeat for frame 3 and 4.

Go back to frame 1, and hit "Ctrl+C" (copy)

Go to frame 5, and hit "Ctrl+V" (paste)

It is not a real "animation loop" feature but it can help achieve your goals. Unfortunately, there is currently no easy way to "select everything from frame X to frame Y", reason why you have to use the rectangle of selection frame by frame :/

Thank you for the tips, I prefer vpaint1.5 interface, he default to the user's creative area is large enough. Frequently used icon buttons are neatly placed on the edge of the interface. The More Parameters dialog box is hidden in the button. Complex graphical user interface is easy for new users to be afraid.

Thank you for the feedback! I agree, I also prefer the way it was in VPaint 1.5 myself. The reason I changed is that on MacOS, drawing the buttons directly over the drawing area (like in VPaint 1.5) is not possible (this is a limitation of the Qt library which I am using). So I changed to something different that works both in Windows and MacOS (and Linux). I prefer to have the same interface between Windows and MacOS so that documentation and tutorials work for both platform, and it is easier to develop and maintain. Anyway, this will most likely change again in future iterations!

Unfortunately, video formats that support an alpha channel are quite rare and not very well supported. I'd suggest instead to export the animation as a sequence of PNG images. However, yes, if I find an easy way to support such formats, I will be happy to do it, since it can be very useful.